wip-hurd: Reviewing my local patches.

[Manolis Ragkousis]

Hello guix, Hello Ludo,

I am sending my local patches for review. Some of the commit messages
may not be right,
but I am mostly sending the patches for code review. All the patches
apply on top of wip-hurd.

When building the bootstrap binaries, glibc-for-bootstrap chooses the
wrong glibc.
The macro I have added  seems to never evaluate to glibc/hurd.

Try ./pre-inst-env guix build --target=i686-pc-gnu bootstrap-tarballs
and see for youself.

Also when I try to do ./pre-inst-env guix build --target=i686-pc-gnu
glibc/hurd , it
ends with stack overflow. The problem seems to be a circular
dependency between hurd-minimal, glibc/hurd headers and glibc/hurd.
This never occurs when building the cross-toolchain.
I am investigating this.

Next are the patches.

Manolis